Changing the subject a little, when I recently moved to the not ready for primetime Windows XP 64 bit edition on my amd 64 machine, I moved away from McAfee and Norton.. I moved to something sugggested by Microsoft personnel. A virus protection program called Avast
Avast! Anti-Virus it runs on both 32 bit and 64 bit windows and is the product of a European company.
Anyway, I stopped using a major brand like McAfee and Symantec/Norton because the virus makers always go after them first, and this one seems to be top notch..
Also it's FREE for home users (including updates). You register the product and it just works. PCLABS gave it a glowing review too. They make money off of the enterprise users but not home users. Gotta love them for that..